Before Closing Air Vents Throughout Your Home, Understand the Effect

October 24, 2013
Ross and Witmer

With energy costs spiraling, anything that might save a buck is tempting to homeowners. Logically, it would seem that blowing heated air into unused rooms is like sending money down the drain. Heating a space you don’t use makes no sense, so shouldn’t closing the air vents (also called registers) in unoccupied rooms save you money?

Why It Seems to Make Sense

Back in the day, wood stoves and fireplaces kept homes warm. Closing to the doors to unused rooms helped to keep the occupied spaces warm. Of course, this meant other rooms were colder, but fuel costs (and effort) were kept to a minimum. And not so long ago–when fuel costs weren’t as high, homes weren’t as energy efficient, and furnaces weren’t as technologically advanced–it was also considered OK to close the doors of unused rooms. As with wood stoves, closing a room made sense.

Why It Doesn’t Make Sense Today

We know more about energy efficiency these days. You’ve probably made an effort to make your home as airtight as possible. You know the importance of well-sealed ductwork, and perhaps you’ve even invested in a high-efficiency furnace that was precisely sized according to your home’s heating load.

So here’s what happens when you close a room in this type of scenario: First, you’ve closed the supply ducts, but you still have an air return in that room. This creates a pressure imbalance. Because of this pressure imbalance, cooler air will be drawn into your room from the outside.

Worse, though, is the effect on your ductwork. The increased pressure finds and exploits leaks and and other weak points in the ducts. The air you’re paying to heat is now leaking into your home’s unconditioned spaces, such as the basement, the garage or the attic.

Long-Term Detriments

Even worse, you could damage your furnace. Modern high-efficiency units are often sized to the specific square footage of your home, within fairly precise tolerances. If the blower fans is forced to churn ’round and ’round in an effort to overcome blockages, it could wear out more quickly.

A trained expert may be able to close off ducts safely by adjusting your furnace’s delivery rate. Contact the specialists at Ross & Witmer to schedule a consultation, and see if closing air vents would work for you. We can also help you develop a long-term energy-savings strategy.

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